This breaks with e.g. -Wa,-O2.
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -36,12 +36,6 @@ message(STATUS "Debug mode ON" )
 else(DEBUG STREQUAL "ON")
 # Release mode
 set(CMAKE_BUILD_TYPE Release)
-set(OPTIMIZE "3" CACHE STRING "Set optimization level (0-3 or DEFAULT)")
-if (NOT OPTIMIZE STREQUAL "DEFAULT")
-  string(REGEX REPLACE "(-O[A-Za-z0-9]+)" "" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
-  string(REGEX REPLACE "(-O[A-Za-z0-9]+)" "" CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}")
-  set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -O${OPTIMIZE}")
-endif()
 message(STATUS "Debug mode OFF")
 message(STATUS "Optimization level ${OPTIMIZE}")